Comparison in Shear Bond Strength of Orthodontic Brackets between Biofix and Conventional Bonding Systems: An in vitro Study

Background and objectives: The aim of the study was to evaluate the shear bond strength of brackets bonded with three bonding systems under laboratory conditions and to compare resin tag penetration after debonding. Materials and methods: The study was done on 60 extracted human premolar teeth, divided into three groups of 20 teeth each. Each group was bonded with three different types of bonding systems namely, the single component bonding system-Biofix, conventional light cured bonding system-Transbond XT and conventional chemical cured bonding system-Unite. The shear bond strength of the bonding system in each group was tested using Instron testing machine. After debonding, the samples were sectioned and viewed under scanning electron microscope to evaluate the resin tag penetration. The depth of penetration was measured with the measuring tool in the scanning electron microscope and marked. Results: The study revealed that the group bonded with Biofix has got the enough bond strength as the conventional chemical cured bonding system, Unite. The resin tag penetration into enamel was seen to be highest for Transbond XT, and for Biofix and Unite it was comparable and less. Conclusion: The shear bond strength values for Biofix is above the needed value to sustain normal oral and orthodontic forces and the residual resin tag remained after debonding are also less. Hence, the single component bonding system Biofix can be considered as a good material of choice for normal clinical bonding procedures.